1. Field of the Invention
The present invention relates to a stable modified metal oxide sol which contains particles comprising colloidal particles of a metal oxide as nuclei and a coating material consisting of an alkali salt of an acidic oxide, colloidal particles of an acidic oxide or a mixture thereof, coated on the surface of the colloidal particles as nuclei, and a process for producing it.
The colloid of the present invention is useful as a component for a hard coating agent to be applied to the surface of plastic lenses.
Further, the present invention relates to a coating composition which provides a coating film having excellent warm water resistance and having no decrease in weather resistance and light resistance even when a vapor deposition film (such as an antireflection film) of an inorganic oxide is provided on the coating film, and an optical element employing the coating composition.
2. Discussion of the Background
In order to improve the surface of plastic lenses which became used widely in recent years, as a component for a hard coating agent to be applied to said surface, sols of a metal oxide having a high refractive index and having a good compatibility with the hard coating agent have been used.
For example, a stable sol of tungstic oxide alone has not been known yet, but a sol having a WO3:SiO2:M2O molar ratio (wherein M is an alkali metal atom or an ammonium group) of 4 to 15:2 to 5:1, obtained by addition of a silicate, has been proposed in JP-A-54-52686.
JP-B-50-40119 proposes a silicate-stanate composite sol having a molar ratio of Si:Sn of 2 to 1000:1.
JP-B-63-37142 discloses a hard coating agent which contains particles of an oxide of a metal such as Al, Ti, Zr, Sn or Sb, having particle diameters of from 1 to 300 nm.
Further, JP-A-3-217230 proposes a stable sol containing colloidal particles of a modified metal oxide having particle diameters of from 4.5 to 60 nm, which comprise colloidal particles of an oxide of a metal with a valence of 3, 4 or 5, having particle diameters of from 4 to 50 nm, as nuclei, and colloidal particles of a tungstic oxide-stannic oxide composite having a WO3/SnO2 weight ratio of from 0.5 to 100 and having particle diameters of from 2 to 7 nm, coated on the surface of the colloidal particles as nuclei, wherein the content of the total metal oxides is from 2 to 50 wt %.
Further, JP-A-6-24746 proposes a stable sol of a modified SnO2-ZrO2 composite which contains particles comprising colloidal particles of a SnO2-ZrO2 composite having a weight ratio of ZrO2/SnO2 of from 0.02 to 1.0 and having particle diameters of from 4 to 50 nm, as nuclei, and colloidal particles of a WO3-SnO2 composite having a WO3/SnO2 weight ratio of from 0.5 to 100 and having particle diameters of from 2 to 7 nm, coated on the surface of the colloidal particles as nuclei.
Still further, JP-A-10-310429 proposes a stable sol of a TiO2-ZrO2-SnO2 composite oxide.
Plastic molded products are used in a large quantity by virtue of their advantageous features such as light weight, good processability and high impact resistance. On the other hand, they have drawbacks that the hardness is inadequate, and thus they are susceptible to scratching, they are likely to be eroded by a solvent, they are likely to be electrified and adsorb a dust, and the heat resistance is inadequate. Thus, as compared with inorganic glass molded products, they were practically inferior for use as lenses for eyeglasses or window materials. Accordingly, it has been proposed to apply a protective coating to a plastic molded product. Many compositions have been proposed as coating compositions to be used for such a protective coating. For example, JP-A-52-11261 proposes to use xe2x80x9ca coating composition containing an organic silicon compound or its hydrolyzate as the main component (resin component or coating film-forming component)xe2x80x9d for eyeglass lenses, which was expected to provide a coating film as hard as an inorganic product. However, this coating composition still does not provide adequate scratch resistance. Accordingly, JP-A-53-111336 proposes one having colloidal silica particles added to the above coating composition, which is used practically for eyeglass lenses.
Heretofore, plastic lenses for eyeglasses have been produced by casting diethylene glycol bisallyl carbonate in a monomer state, followed by polymerization. The lenses produced in such a manner have a refractive index of about 1.50, which is low as compared with the refractive index of about 1.52 of glass lenses, and in the case of lenses for short sighted, there is a problem that the peripheral thickness has to be increased. Accordingly, in recent years, there has been development of monomers having higher refractive indices than the diethylene glycol bisallyl carbonate. For example, resin materials having high refractive indices are proposed, for example, in JP-A-55-13747, JP-A-56-166214, JP-A-57-23611, JP-A-57-54901, JP-A-59-133211, JP-A-60-199016 and JP-A-64-54021.
For lenses made of such resins having high refractive indices, JP-A-62-151801 and JP-A-63-275682 propose a method of using a colloidal dispersion of fine particles of an oxide of a metal such as Sb or Ti, for a coating material.
If such a conventional metal oxide sol, particularly a cationic metal oxide sol, is used as a component for a hard coating agent, not only the stability of the obtained hard coating agent tends to be insufficient, but also e.g. transparency, adhesion and weather resistance of the cured coating of the hard coating agent tend to be insufficient. Further, in a case where a Sb2O5 sol is used as a component for a hard coating agent, the refractive index of the cured coating will no longer increase adequately with this Sb2O5 sol if the refractive index of the plastic substrate for a lens is at least 1.60, since the refractive index of Sb2O5 is a level of from 1.65 to 1.70.
The above sol of tungstic oxide as disclosed in JP-A-54-52686 is obtained by adding a silicate to an aqueous solution of tungstic oxide obtainable by subjecting an aqueous solution of a tungstate to cation exchange. However, the sol is stable only in a strong acidic condition, and its effect to increase the refractive index of the coating film is small when used as a component for a hard coating agent.
The above silicate-stannate composite sol as disclosed in JP-B-50-40119 is obtained by subjecting a mixed aqueous solution of an alkali silicate and an alkali stannate to cation exchange. However, its effect to increase the refractive index of the coating film is also small when used as a component for a hard coating agent.
The coating composition having a silica sol added thereto, has a problem that the coating film is likely to have interference fringes which impair the appearance of the lenses. Further, in lenses, an antireflection film (composed of a multilayer structure film comprising thin films of inorganic oxides, based on an optical interference theory) is formed in many cases, on the coating film. In such a case, the antireflection film tends to exhibit, for example, a reflection color of extremely pale green, and this reflection color changes depending upon the position on the lens surface to form flecking.
A coating composition prepared by using a titanium oxide sol has a problem that the titanium oxide sol has a low compatibility with a silane coupling agent or its hydrolyzate, the stability tends to be low, and the coating layer formed by this coating composition tends to be poor in water resistance and tends to be blued by irradiation with ultraviolet rays.
It is an object of the present invention to provide a stable sol containing colloidal particles of a modified metal oxide which is stable in a wide pH range, and which further increases the properties of a hard coating film employing the modified metal oxide sol as disclosed in JP-A-3-217230 or JP-A-6-24746, such as scratch resistance, transparency, adhesion, water resistance and weather resistance.
Another object of the present invention to provide a coating composition which is capable of forming a coating film free from interference fringes or flecking in reflection colors, on a plastic molded product having a moderate to high refractive index of nd=1.54-1.70, and an optical element employing the coating composition. Further, it is to provide a coating composition for plastic molded products excellent in e.g. scratch resistance, surface hardness, abrasion resistance, flexibility, transparency, antistatic property, dyability, heat resistance, water resistance and chemical resistance, and an optical element employing the coating composition.
According to a first aspect of the present invention, there is provided a stable modified metal oxide sol which contains from 2 to 50 wt %, as calculated as metal oxides, of particles (c) comprising colloidal particles (a) of a metal oxide having primary particle diameters of from 2 to 60 nm, as nuclei, and a coating material (b) consisting of colloidal particles of an acidic oxide coated on the surface of the particles (a), and which has primary particle diameters of from 2 to 100 nm.
According to a second aspect of the present invention, there is provided the modified metal oxide sol according to the first aspect of the present invention, wherein the metal oxide as the nuclei is an oxide of at least one metal selected from the group consisting of Ti, Fe, Cu, Zn, Y, Zr, Nb, Mo, In, Sn, Sb, Ta, W, Pb, Bi and Ce.
According to a third aspect of the present invention, there is provided the modified metal oxide sol according to the first or second aspect of the present invention, wherein the acidic oxide to be used for the coating material (b), is antimony oxide.
According to a fourth aspect of the present invention, there is provided the modified metal oxide sol according to any one of the first to third aspects of the present invention, wherein the coating material (b) is an antimony pentoxide colloid containing an alkali component.
According to a fifth aspect of the present invention, there is provided the modified metal oxide sol according to the fourth aspect of the present invention, wherein the coating material (b) contains an alkali component consisting of an alkylamine, and has a M/Sb2O5 molar ratio (wherein M is an amine molecule) of from 0.02 to 4.00.
According to a six aspect of the present invention, there is provided the modified metal oxide sol according to any one of the first to fifth aspects of the present invention, wherein the coating material (b) further contains an alkylamine-containing silica.
According to a seventh aspect of the present invention, there is provided a process for producing the modified metal oxide sol as defined in the first aspect of the present invention, which comprises mixing an aqueous sol containing the colloidal particles (a) of a metal oxide as nuclei, and an aqueous sol containing the coating material (b), in a weight ratio of (b)/(a) of from 0.01 to 1 as calculated as metal oxides, and heating the aqueous medium.
According to an eighth aspect of the present invention, there is provided a process for producing the modified metal oxide sol as defined in the first aspect of the present invention, which comprises mixing an aqueous sol containing the colloidal particles (a) of a metal oxide as nuclei, and an aqueous solution of a water-soluble alkali antimonate as the coating material (b), in a weight ratio of (b)/(a) of from 0.01 to 1 as calculated as metal oxides, and heating the aqueous medium, followed by cation exchange.
According to a ninth aspect of the present invention, there is provided a coating composition comprising the following components (A) and (B):
component (A): at least one silicon-containing substance selected from the group consisting of organic silicon compounds of the formula (I):
(R1)a(R3)bSi(OR2)4xe2x88x92(a+b)xe2x80x83xe2x80x83(I)
wherein each of R1 and R3 is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkenyl group, or an organic group having an epoxy group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group or a cyano group, which is bonded to the silicon atom by a Sixe2x80x94C bond, R2 is a C1-8 alkyl group, an alkoxyalkyl group or an acyl group, and each of a and b is an integer of 0, 1 or 2, provided that a+b is an integer of 0, 1 or 2, and the formula (II):
[(R4)cSi(OX)3 xe2x88x92c]2Yxe2x80x83xe2x80x83(II)
wherein R4 is a C1-5 alkyl group, X is a C1-4 alkyl group or an acyl group, Y is a methylene group or a C2-20 alkylene group, and c is an integer of 0 or 1, and their hydrolyzates; and
component (B): colloidal particles of a modified metal oxide which have primary particle diameters of from 2 to 100 nm and which contain particles (c) comprising colloidal particles (a) of a metal oxide having primary particle diameters of from 2 to 60 nm, as nuclei, and a coating material (b) consisting of colloidal particles of an acidic oxide coated on the surface of the particles (a).
According to a tenth aspect of the present invention, there is provided the coating composition according to the ninth aspect of the present invention, wherein the component (A) is at least one silicon-containing substance selected from the group consisting of the organic silicon compounds of the formula (I) and their hydrolyzates.
According to an eleventh aspect of the present invention, there is provided the coating composition according to the ninth or tenth aspects of the present invention, wherein the metal oxide to be used for the nuclei of the component (B) is an oxide of at least one metal selected from the group consisting of Ti, Fe, Cu, Zn, Y, Zr, Nb, Mo, In, Sn, Sb, Ta, W, Pb, Bi and Ce.
According to a twelfth aspect of the present invention, there is provided the coating composition according to any one of the ninth to eleventh aspects of the present invention, wherein the acidic oxide to be used for the coating material (b) of the component (B), is antimony oxide.
According to a thirteenth aspect of the present invention, there is provided the coating composition according to any one of the ninth to twelfth aspects of the present invention, wherein the coating material (b) of the component (B) is a diantimony pentoxide colloid containing an alkali component.
According to a fourteenth aspect of the present invention, there is provided the coating composition according to the thirteenth aspect of the present invention, wherein the coating material (b) of the component (B) contains an alkali component consisting of an alkylamine, and has a M/Sb2O5 molar ratio (wherein M is an amine molecule) of from 0.02 to 4.00.
According to a fifteenth aspect of the present invention, there is provided the coating composition according to any one of the ninth to fourteenth aspects of the present invention, wherein the coating material (b) of the component (B) further contains an alkylamine-containing silica.
According to a sixteenth aspect of the present invention, there is provided the coating composition according to any one of the ninth to fifteenth aspects of the present invention, which contains at least one curing catalyst selected from the group consisting of metal salts, metal alkoxides and metal chelates.
According to a seventeenth aspect of the present invention, there is provided an optical element which comprises an optical substrate and a cured film made of the coating composition as defined in any one of the ninth to sixteenth aspects of the present invention, formed on the surface of the optical substrate.
According to an eighteenth aspect of the present invention, there is provided the optical element according to the seventeenth aspect of the present invention, which further has an antireflection film formed on its surface.
Now, the present invention will be described in detail with reference to the preferred embodiments.
According to the first aspect, the present invention provides a stable modified metal oxide sol which contains from 2 to 50 wt %, as calculated as metal oxides, of particles (c) comprising colloidal particles (a) of a metal oxide having primary particle diameters of from 2 to 60 nm, as nuclei, and a coating material (b) consisting of colloidal particles of an acidic oxide coated on the surface of the particles (a), and which has primary particle diameters of from 2 to 100 nm.
Here, with respect to the primary particle diameters, a primary sol is a sol wherein particles are dispersed as individual particles, or in a state close thereto. The particles in such a primary sol are referred to as primary particles, and the primary particle diameters are diameters of such primary particles. A secondary sol is a sol wherein several primary particles in the primary sol agglomerate. In the present invention, diameters of particles (a) as nuclei, colloidal particles (b) for coating and particles (c) of a modified metal oxide are all represented by primary particle diameters. Each diameter is not a diameter of an agglomerated particle of (a), (b) or (c), but a diameter of an individual particle (a), (b) or (c) when an agglomerated particle has been dissociated into individual particles (a), (b) or (c), and such primary particle diameters can be measured by an electron microscope.
Colloidal particles (a) of a metal oxide having primary particle diameters of from 2 to 60 nm may be produced by a known method such as an ion exchange method, a peptization method, a hydrolysis method or a reaction method. Examples of the ion exchange method include a method of treating an acid salt of the above metal with a hydrogen form ion exchange resin, and a method of treating a basic salt of the above metal with a hydroxyl group form anion exchange resin. Examples of the peptization method include a method of washing a gel obtained by neutralizing an acid salt of the above metal with a base or by neutralizing a basic salt of the above metal with an acid, followed by peptization with an acid or a base. Examples of the above hydrolysis method include a method of hydrolyzing an alkoxide of the above metal, and a method of hydrolyzing a basic salt of the above metal under heating, followed by removal of an unnecessary acid. Examples of the reaction method include a method of reacting a powder of the above metal with an acid. A metal oxide as the nuclei is an oxide of at least one metal selected from the group consisting of Ti, Fe, Cu, Zn, Y, Zr, Nb, Mo, In, Sn, Sb, Ta, W, Pb, Bi and Ce. Colloidal particles (A) of this metal oxide is an oxide of a metal having a valence of from 2 to 6, and the form of the oxide of such a metal may, for example, be TiO2, Fe2O3, CuO, ZnO, Y2O3, ZrO2, Nb2O5, MoO3, In2O3, SnO2, Sb2O5, Ta2O5, WO3, PbO or Bi2O3. These metal oxides may be used alone or in combination. When they are used as combined, several types of the above metal oxides are mixed, the above metal oxides are made into a composite, or the above metal oxides are made into a solid solution at a level of atoms. For example, colloidal particles of a SnO2-WO3 composite wherein SnO2 particles and WO3 particles are chemically bonded at their interfaces to form a composite, colloidal particles of a SnO2-ZrO2 composite wherein SnO2 particles and ZrO2 particles are chemically bonded at their interfaces to form a composite, or colloidal particles of a TiO2-ZrO2-SnO2 composite wherein TiO2, ZrO2 and SnO2 are formed into a solid solution at a level of atoms, may be mentioned. The oxide of a metal to be used for nuclei, may be used as a compound by combination of metal components, and examples of which include ZnSb2O6, InSbO4 and ZnSnO3.
In the first aspect of the present invention, particles (c) comprising colloidal particles (a) of a metal oxide as nuclei, and a coating material (b) consisting of colloidal particles of an acidic oxide coated on the surface of the particles (a), is obtained. As the acidic oxide to be used for the coating material (b), antimony oxide may be used.
As the coating material (b), a diantimony pentoxide colloid containing an alkali component is preferably used.
The diantimony pentoxide colloid containing an alkali component may be obtained by the following methods (e.g. oxidation method and acid decomposition method).
Examples of the acid decomposition method include a method of reacting an alkali antimonate with an inorganic acid, followed by peptization with an amine (JP-A-60-41536, JP-A-61-227918). Examples of the oxidation method include a method of oxidizing diantimony trioxide with hydrogen peroxide in the presence of an amine or an alkali metal (JP-B-57-11848, JP-A-59-232921), and a method of oxidizing diantimony trioxide with hydrogen peroxide, and then adding an amine or an alkali metal thereto.
The alkali component in the diantimony pentoxide colloid containing an alkali component, may, for example, be an alkali metal, ammonium, a quaternary ammonium or a water-soluble amine. Among these, preferred are Na, K and NH3, alkylamines such as isopropylamine, diisopropylamine, n-propylamine and diisobutylamine, aralkylamines such as benzylamine, alicyclic amines such as piperidine, and alkanolamines such as monoethanolamine and triethanolamine. Particularly preferred as an alkali metal is potassium, and preferred as an organic base is diisopropylamine. The molar ratio of the alkali component to the diantimony pentoxide, i.e. M/Sb2O5, is preferably from 0.02 to 4.00 in the diantimony pentoxide colloid containing an alkali component. If it is smaller than this range, the stability of the colloid to be obtained tends to be poor, and if it is higher than this range, the dried coating film to be obtained by using such a sol tends to have a low water resistance, such being undesirable practically.
Colloidal particles of diantimony pentoxide containing an alkali component are fine colloidal particles of diantimony pentoxide, and have primary particle diameters of from about 1 to about 20 nm as observed by an electron microscope. As the alkali component, preferred is an amine salt of e.g. diisopropylamine, and the molar ratio of amine/Sb2O5 is from 0.02 to 4.00.
With respect to the above coating material (b), an alkylamine-containing silica particles may further be added to colloidal particles of diantimony pentoxide containing an alkali component.
As a process for producing the modified metal oxide sol of the present invention, a first process is a process of mixing an aqueous sol containing the colloidal particles (a) of a metal oxide as nuclei, and an aqueous sol containing the coating material (b), in a weight ratio of (b)/(a) of from 0.01 to 1 as calculated as metal oxides, and heating the aqueous medium. For example, an aqueous sol containing colloidal particles (a) of a metal oxide and a sol containing colloidal particles (b) of diantimony pentoxide containing an alkylamine as the alkali component, are mixed in the above ratio, followed by heating the aqueous medium, to obtain a modified metal oxide sol containing particles (c) comprising colloidal particles (a) as nuclei and colloidal particles (b) of diantimony pentoxide containing an alkali component coated on the surface of the colloidal particles (a).
Further, a second process for producing the modified metal oxide sol is a process of mixing an aqueous sol containing colloidal particles (a) of a metal oxide as nuclei, and an aqueous solution of a water-soluble alkali antimonate as the coating material (b), in a weight ratio of (b)/(a) of from 0.01 to 1 as calculated as metal oxides, and heating the aqueous medium, followed by cation exchange. The aqueous solution of a water-soluble alkali antimonate to be used in said second process is preferably an aqueous solution of potassium antimonate. For example, an aqueous sol containing colloidal particles (a) of a metal oxide, and an aqueous solution of potassium antimonate as the coating material (b), are mixed and heated, and then ion exchange is carried out, followed by stabilization with an alkali component such as an alkylamine, to obtain a modified metal oxide sol containing particles (c) comprising colloidal particles (a) and colloidal particles (b) of diantimony pentoxide containing an alkali component coated on the surface of the colloidal particles (a).
In the above first or second process, in a case where the colloidal particles (a) of a metal oxide as nuclei are in a form of an acid sol, the colloidal particles (a) may be mixed with colloidal particles of diantimony pentoxide containing an alkylamine as an alkali component or a water-soluble alkali antimonate as the coating material (b), in a weight ratio (b)/(a) of from 0.01 to 1 as calculated as metal oxides, and anion exchange of the aqueous medium may be carried out to obtain colloidal particles (axe2x80x2), and an aqueous medium containing colloidal particles (axe2x80x2) may be heated in the above first process, or an aqueous medium containing colloidal particles (axe2x80x2) may be heated and subjected to cation exchange, followed by stabilization with an alkali component such as an alkylamine, in the above second process, to obtain a modified metal oxide sol.
The above mixing may be carried out at a temperature of from 0 to 100xc2x0 C., preferably from room temperature to 60xc2x0 C. It is possible to carry out the heating by using an autoclave at a temperature of at least 100xc2x0 C., but it is carried out preferably at a temperature of from 70 to 95xc2x0 C.
It is preferred to select concentrations of both components to be used for the mixing before the mixing so that the sol of modified colloidal particles (c) to be obtained by the mixing contains the metal oxide of the component (a) and the coating material component (b) as calculated as oxide in a total amount of from 2 to 40 wt %.
The modified metal oxide sol according to the first aspect of the present invention may contain an optional component so long as the purpose of the present invention is achieved. Particularly when an oxycarboxylic acid is contained in an amount of at most about 30 wt % based on the total amount of metal oxides, a colloid having further improved performances such as dispersibility, will be obtained. Examples of the oxycarboxylic acid to be used include lactic acid, tartaric acid, citric acid, gluconic acid, malic acid and glycollic acid. Further, an alkali component may be contained, such as an alkali metal hydroxide of e.g. Li, Na, K, Rb or Cs; NH4, an alkylamine such as ethylamine, triethylamine, isopropylamine or n-propylamine; an aralkylamine such as benzylamine, an alicyclic amine such as piperidine; or an alkanolamine such as monoethanolamine or triethanolamine. They may be used in combination as a mixture of two or more of them. Further, they may be used together with the above acid component. They may be contained in an amount of at most about 30 wt % based on the total amount of the metal oxides.
In order to further increase the sol concentration, it is possible to carry out concentration up to a level of 50 wt % by a conventional method such as a distillation method or an ultrafiltration method. To adjust the pH of the sol, e.g. the above alkali metal, organic base (amine) or oxycarboxylic acid may be added to the sol after the concentration. Particularly, a sol having a total concentration of the metal oxides of from 10 to 40 wt % is practically preferred.
When the modified metal oxide colloid obtained by the above mixing is an aqueous sol, an organosol may be obtained by replacing the aqueous medium in the aqueous sol with a hydrophilic organic solvent. This replacement may be carried out by a conventional method such as a distillation method or an ultrafiltration method. Examples of the hydrophilic organic solvent include lower alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; linear amides such as dimethylformamide and N,Nxe2x80x2-dimethylacetamide; cyclic amides such as N-methyl-2-pyrrolidone; and glycols such as ethyl cellosolve and ethylene glycol.
According to the ninth aspect, the present invention provides a coating composition comprising the following components (A) and (B):
component (A): at least one silicon-containing substance selected from the group consisting of organic silicon compounds of the formula (I):
(R1)a(R3)bSi(OR2)4xe2x88x92(a+b)xe2x80x83xe2x80x83(I)
wherein each of R1 and R3 is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkenyl group, or an organic group having an epoxy group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group or a cyano group, which is bonded to the silicon atom by a Sixe2x80x94C bond, R2 is a C1-8 alkyl group, an alkoxyalkyl group or an acyl group, and each of a and b is an integer of 0, 1 or 2, provided that a+b is an integer of 0, 1 or 2, and the formula (II):
[(R4)cSi(OX)3xe2x88x92c]2Yxe2x80x83xe2x80x83(II)
wherein R4 is a C1-5 alkyl group, X is a C1-4 alkyl group or an acyl group, Y is a methylene group or a C2-20 alkylene group, and c is an integer of 0 or 1, and their ydrolyzates; and
component (B): colloidal particles of a modified metal oxide which have primary particle diameters of from 2 to 100 nm and which contain particles (c) comprising colloidal particles (a) of a metal oxide having primary particle diameters of from 2 to 60 nm, as nuclei, and a coating material (b) consisting of colloidal particles of an acidic oxide coated on the surface of the particles (a).
The formula (I) for component (A) to be used for the coating composition according to the ninth aspect of the present invention:
(R1)a(R3)bSi(OR2)4xe2x88x92(a+b)xe2x80x83xe2x80x83(I)
includes an organic silicon compound wherein R1 and R3 are the same organic groups or different organic groups, and a and b are the same integers or different integers. The organic silicon compound of the formula (I) for component (A) may, for example, be tetramethoxysilane, tetraethoxysilane, tetra n-propoxysilane, tetraisopropoxysilane, tetra n-butoxysilane, tetraacetoxysilane, methyltrimethoxysilane, methyltripropoxysilane, methyltriacetoxysilane, methyltributoxysilane, methyltripropoxysilane, methyltriamyloxysilane, methyltriphenoxysilane, methyltribenzyloxysilane, methyltriphenetyloxysilane, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, xcex1-glycidoxyethyltrimethoxysilane, xcex1-glycidoxyethyltriethoxysilane, xcex2-glycidoxyethyltrimethoxysilane, xcex2-glycidoxyethyltriethoxysilane, xcex1-glycidoxypropyltrimethoxysilane, xcex1-glycidoxypropyltriethoxysilane, xcex2-glycidoxypropyltrimethoxysilane, xcex2-glycidoxypropyltriethoxysilane, xcex3-glycidoxypropyltrimethoxysilane, xcex3-glycidoxypropyltriethoxysilane, xcex3-glycidoxypropyltripropoxysilane, xcex3-glycidoxypropyltributoxysilane, xcex3-glycidoxypropyltriphenoxysilane, xcex1-glycidoxybutyltrimethoxysilane, xcex1-glycidoxybutyltriethoxysilane, xcex2-glycidoxybutyltriethoxysilane, xcex3-glycidoxybutyltriethoxysilane, xcex3-glycidoxybutyltriethoxysilane, xcex4-glycidoxybutyltrimethoxysilane, xcex4-glycidoxybutyltriethoxysilane, (3,4-epoxycyclohexyl)methyltrimethoxysilane, (3,4-epoxycyclohexyl)methyltriethoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltripropoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltributoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltriphenoxysilane, xcex3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, xcex3-(3,4-epoxycyclohexyl)propyltriethoxysilane, xcex4-(3,4-epoxycyclohexyl)butyltrimethoxysilane, xcex4-(3,4-epoxycyclohexyl)butyltriethoxysilane, glycidoxymethylmethyldimethoxysilane, glycidoxymethylmethyldiethoxysilane, xcex1-glycidoxyethylmethyldimethoxysilane, xcex1-glycidoxyethylmethyldiethoxysilane, xcex2-glycidoxyethylmethyldimethoxysilane, xcex2-glycidoxyethylethyldimethoxysilane, xcex1-glycidoxypropylmethyldimethoxysilane, xcex1-glycidoxypropylmethyldiethoxysilane, xcex2-glycidoxypropylmethyldimethoxysilane, xcex2-glycidoxypropylethyldimethoxysilane, xcex3-glycidoxypropylmethyldimethoxysilane, xcex3-glycidoxypropylmethyldiethoxysilane, xcex3-glycidoxypropylmethyldipropoxysilane, xcex3-glycidoxypropylmethyldibutoxysilane, xcex3-glycidoxypropylmethyldiphenoxysilane, xcex3-glycidoxypropylethyldimethoxysilane, xcex3-glycidoxypropylethyldiethoxysilane, xcex3-glycidoxypropylvinyldimethoxysilane, xcex3-glycidoxypropylvinyldiethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, xcex3-chloropropyltrimethoxysilane, xcex3-chloropropyltriethoxysilane, xcex3-chloropropyltriacetoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, xcex3-methacryloxypropyltrimethoxysilane, xcex3-mercaptopropyltrimethoxysilane, xcex3-mercaptopropyltriethoxysilane, xcex2-cyanoethyltriethoxysilane, chloromethyltrimethoxysilane, chloromethyltriethoxysilane, N-(xcex2-aminoethyl) xcex3-aminopropyltrimethoxysilane, N-(xcex2-aminoethyl) xcex3-aminopropylmethyldimethoxysilane, xcex3-aminopropylmethyldimethoxysilane, N-(xcex2-aminoethyl) xcex3-aminopropyltriethoxysilane, N-(xcex2-aminoethyl) xcex3-aminopropylmethyldiethoxysilane, dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, xcex3-chloropropylmethyldimethoxysilane, xcex3-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane, xcex3-methacryloxypropylmethyldimethoxysilane, xcex3-methacryloxypropylmethyldiethoxysilane, xcex3-mercaptopropylmethyldimethoxysilane, xcex3-mercaptomethyldiethoxysilane, methylvinyldimethoxysilane, or methylvinyldiethoxysilane. These organic silicon compounds may be used alone or in combination as a mixture of two or more of them.
The hydrolyzates of organic silicon compounds of the formula (I) for component (A) to be used for the coating composition according to the ninth aspect of the present invention, are compounds obtained by hydrolysis of the organic silicon compounds of the formula (I) so that a part or all of R2 is substituted by hydrogen atoms. Such hydrolyzates of the organic silicon compounds of the formula (I) may be used alone or in combination as a mixture of two or more of them. The hydrolysis is carried out by adding an aqueous acidic solution such as an aqueous hydrochloric acid solution, an aqueous sulfuric acid solution or an aqueous acetic acid solution to the organic silicon compound, followed by stirring.
The organic silicon compound of the formula (II):
[R4)cSi(OX)3xe2x88x92c]2Yxe2x80x83xe2x80x83(II)
for component (A) to be used for the coating composition according to the ninth aspect of the present invention, may, for example, be methylenebismethyldimethoxysilane, ethylenebisethyldimethoxysilane, propylenebisethyldiethoxysilane or butylenebismethyldiethoxysilane. These organic silicon compounds may be used alone or in combination as a mixture of two or more of them.
The hydrolyzates of organic silicon compounds of the formula (II) for component (A) to be used for the coating composition according to the ninth aspect of the present invention, are compounds obtained by hydrolysis of the organic silicon compounds of the formula (II) so that a part or all of X is substituted by hydrogen atoms. Such hydrolyzates of the organic silicon compounds of the formula (II) may be used alone or in combination as a mixture of two or more of them. The hydrolysis is carried out by adding an aqueous acidic solution such as an aqueous hydrochloric acid solution, an aqueous sulfuric acid solution or an aqueous acetic acid solution to the organic silicon compound, followed by stirring.
Component (A) to be used for the coating composition according to the ninth aspect of the present invention, is at least one silicon-containing substance selected from the group consisting of organic silicon compounds of the formulae (I) and (II) and their hydrolyzates.
Component (A) to be used for the coating composition according to the ninth aspect of the present invention, is preferably at least one silicon-containing substance selected from the group consisting of organic silicon compounds of the formula (I) and their hydrolyzates. Particularly preferred are organic silicon compounds of the formula (I) wherein either one of R1 and R3 is an organic group having an epoxy group, R2 is an alkyl group, and each of a and b is 0 or 1, provided that a+b is 1 or 2, and their hydrolyzates. Examples of such preferred organic silicon compounds include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, xcex1-glycidoxyethyltrimethoxysilane, xcex1-glycidoxyethyltriethoxysilane, xcex2-glycidoxyethyltrimethoxysilane, xcex2-glycidoxyethyltriethoxysilane, xcex1-glycidoxypropyltrimethoxysilane, xcex1-glycidoxypropyltriethoxysilane, xcex2-glycidoxypropyltrimethoxysilane, xcex2-glycidoxypropyltriethoxysilane, xcex3-glycidoxypropyltrimethoxysilane, xcex3-glycidoxypropyltriethoxysilane, xcex3-glycidoxypropyltripropoxysilane, xcex3-glycidoxypropyltributoxysilane, xcex3-glycidoxypropyltriphenoxysilane, xcex1-glycidoxybutyltrimethoxysilane, xcex1-glycidoxybutyltriethoxysilane, xcex2-glycidoxybutyltriethoxysilane, xcex3-glycidoxybutyltrimethoxysilane, xcex3-glycidoxybutyltriethoxysilane, xcex4-glycidoxybutyltrimethoxysilane, xcex4-glycidoxybutyltriethoxysilane, glycidoxymethylmethyldimethoxysilane, glycidoxymethylmethyldiethoxysilane, xcex1-glycidoxyethylmethyldimethoxysilane, xcex1-glycidoxyethylmethyldiethoxysilane, xcex2-glycidoxyethylmethyldimethoxysilane, xcex2-glycidoxyethylethyldimethoxysilane, xcex1-glycidoxypropylmethyldimethoxysilane, xcex1-glycidoxypropylmethyldiethoxysilane, xcex2-glycidoxypropylmethyldimethoxysilane, xcex2-glycidoxypropylethyldimethoxysilane, xcex3-glycidoxypropylmethyldimethoxysilane, xcex3-glycidoxypropylmethyldiethoxysilane, xcex3-glycidoxypropylmethyldipropoxysilane, xcex3-glycidoxypropylmethyldibutoxysilane, xcex3-glycidoxypropylmethyldiphenoxysilane, xcex3-glycidoxypropylethyldimethoxysilane, xcex3-glycidoxypropylethyldiethoxysilane, xcex3-glycidoxypropylvinyldimethoxysilane, and xcex3-glycidoxypropylvinyldiethoxysilane.
More preferred are xcex3-glycidoxypropyltrimethoxysilane, xcex3-glycidoxypropylmethyldiethoxysilane, xcex3-glycidoxypropylmethyldimethoxysilane and their hydrolyzates, and they may be used alone or in combination as a mixture. Further, xcex3-glycidoxypropyltrimethoxysilane, xcex3-glycidoxypropylmethyldiethoxysilane, xcex3-glycidoxypropylmethyldimethoxysilane or a hydrolyzate thereof may be used in combination with a tetrafunctional compound of the formula (I) wherein a+b =0. Examples of the tetrafunctional compound include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetra n-propoxysilane, tetra n-butoxysilane, tetra tert-butoxysilane and tetra sec-butoxysilane.
Component (B) to be used for the coating composition according to the ninth aspect of the present invention, is preferably a sol containing colloidal particles of a modified metal oxide, which contains from 2 to 50 wt %, as calculated as metal oxides, of particles (c) comprising colloidal particles (a) of a metal oxide having primary particle diameters of from 2 to 60 nm, as nuclei, and a coating material (b) consisting of colloidal particles of an acidic oxide coated on the surface of the particles (a), and which has primary particle diameters of from 2 to 100 nm. As such a modified metal oxide sol, the modified metal oxide sol according to the first aspect of the present invention, may be used.
The coating composition according to the ninth aspect of the present invention preferably contains from 1 to 500 parts by weight of colloidal particles of a modified metal oxide which contain particles (c) comprising colloidal particles (a) of a metal oxide having primary particle diameters of from 2 to 60 nm, as nuclei, and a coating material (b) consisting of colloidal particles of an acidic oxide coated on the surface of the colloidal particles (a), and which have primary particle diameters of from 2 to 100 nm, based on 100 parts by weight of an organic silicon compound. If the modified metal oxide sol is less than 1 part by weight, the cured film tends to have a low refractive index, and application to a substrate will be significantly limited. Further, if it exceeds 500 parts by weight, e.g. cracks are likely to form between the cured film and the substrate, and there is a high possibility of decrease in transparency.
To the coating composition according to the ninth aspect of the present invention, a curing agent may be incorporated so as to accelerate the reaction, fine particulate of a metal oxide may be incorporated so as to adjust the refractive index with lenses to be various substrates, or a surface active agent may be incorporated so as to improve wettability at the time of coating and to improve smoothness of the cured film. Further, e.g. an ultraviolet absorber or an antioxidant may be added within a range of not impairing physical properties of the cured film.
The curing agent may, for example, be an amine such as allylamine or ethylamine, a salt or a metal salt having an acid or a base containing a Lewis acid or a Lewis base, such as organic carboxylic acid, chromic acid, hypochlorous acid, boric acid, perchloric acid, bromic acid, selenious acid, thiosulfuric acid, orthosilicic acid, thiocyanic acid, nitrous acid, aluminic acid or carbonic acid, or an alkoxide or chelate of a metal such as aluminum, zirconium or titanium.
Further, the fine particulate metal oxide may, for example, be fine particles of e.g. aluminum oxide, titanium oxide, antimony oxide, zirconium oxide, silicon oxide or cerium oxide.
According to the seventeenth aspect of the present invention, there is provided an optical element which comprises an optical substrate and a cured film made of the coating composition according to the ninth aspect of the present invention formed on the surface of the optical substrate. Further, according to the eighteenth aspect of the present invention, there is provided the optical element which further has an antireflection film formed on its surface.
The coating composition according to the ninth aspect of the present invention may be coated on a substrate, followed by curing, to obtain a cured film. The present invention further provides an optical element which has a cured film made of the above coating composition, a shock absorbing film, and an antireflection film laminated on its surface. Curing of the coating composition may be carried out by hot air drying or irradiation with active energy rays. As the curing conditions, curing is preferably carried out in a hot air of from 70 to 200xc2x0 C., particularly preferably from 90 to 150xc2x0 C. As the active energy rays, far infrared rays may be used, whereby damage due to heat can be suppressed to a low level.
As a method of forming the cured film made of the coating composition according to the ninth aspect of the present invention on a substrate, the above method of coating the coating composition on a substrate, may be mentioned. As a coating means, a conventional method such as a dipping method, a spin coating method or a spray coating method may be employed. However, a dipping method or a spin coating method is particularly preferred from the viewpoint of the area degree.
Further, adhesion between the substrate and the cured film may be improved by applying chemical treatment by means of an acid, an alkali or various organic solvents, physical treatment by means of plasma or ultraviolet rays, washing treatment by means of various washing agents or primer treatment by means of various resins, prior to coating the above coating composition on the substrate.
Further, an antireflection film of vapor deposition film of an inorganic oxide may be formed on the cured film made of the above coating composition. The antireflection film is not particularly limited, and a conventionally known single-layer or multilayer antireflection film of a vapor deposition film of an inorganic oxide may be used. Examples of the antireflection film include antireflection films as disclosed in JP-A-2-262104 and JP-A-56-116003.
The shock absorbing film will improve a shock resistance of the optical element. The shock absorbing film is made of a polyvinyl alcohol resin, polyvinyl acetate resin, or polyacrylic acid resin, etc.
Further, the cured film made of the coating composition is useful as an antireflection film as a high refractive index film. Further, by incorporating a functional component for e.g. antifogging, photochromic or stain proofing, it may also be used as a multifunctional film.
The optical element having the cured film made of the coating composition is useful as not only lenses for eyeglasses, but also lenses for cameras, window glasses for automobiles and optical filters for liquid crystal display or plasma display devices.